CELL PERFORMANCE ESTIMATION METHOD AND CELL PERFORMANCE ESTIMATION APPARATUS

• US 20140222358A1
• Filed: 01/30/2014
• Published: 08/07/2014
• Est. Priority Date: 02/04/2013
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: MORITA, Tomokazu, HOSHINO, Masayuki
• Application Number:
  US14/168,113
• Publication Number:
  US 20140222358A1
• Time in Patent Office: Days
• US Class Current: 702/63
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery

Abstract

According to one embodiment, a cell performance estimation method includes storing data obtained by measuring a cell temperature, an electric current, and a voltage while a secondary cell is charged or discharged, estimating an internal resistance value of the cell by using the cell temperature data, the electric current data, and the voltage data, and predetermined data indicating a relationship between a charged capacity and open circuit voltages of a cathode active material and anode active material, calculating a reaction resistance component, an ohmic resistance component, and a diffusion resistance component from the estimated internal resistance value and correcting the estimated internal resistance value based on a value obtained by correcting the reaction resistance component, the ohmic resistance component, and the diffusion resistance component in accordance with a temperature, and adding up the corrected values.

Claims

1. A cell performance estimation method comprising:

storing data obtained by measuring a cell temperature, an electric current, and a voltage while a secondary cell is charged or discharged;

estimating an internal resistance value of the cell by using the cell temperature data, the electric current data, and the voltage data, and predetermined data indicating a relationship between a charged capacity and open circuit voltages of a cathode active material and anode active material;

calculating a reaction resistance component, an ohmic resistance component, and a diffusion resistance component from the estimated internal resistance value; and

correcting the estimated internal resistance value based on a value obtained by correcting the reaction resistance component, the ohmic resistance component, and the diffusion resistance component in accordance with a temperature, and adding up the corrected values.

2. The method according to claim 1, wherein in the estimating, the data indicating the relationship between the charged capacity and the open circuit voltages of the cathode active material and anode active material is corrected in accordance with a temperature based on data indicating a relationship between an entropy value of each active material and the charged capacity, with respect to a cell temperature at which the data indicating the relationship between the charged capacity and the open circuit voltages of the cathode active material and anode active material is measured.

3. The method according to claim 1, wherein in the correcting, when using coefficients Ea, Eb, Ec, and R1 to be used in the temperature correction of the secondary cell and a cell temperature T, temperature correction of a reaction resistance component Rct, a diffusion resistance component Rd, and an ohmic resistance component Rohm is performed at a reference temperature T₀ as follows:

Rct(T₀)=Rct(T)×

Exp(−

Ea/(R·

T))/Exp(−

Ea/(R·

T₀))

Rd(T₀)=Rd(T)×

Exp(−

Eb/(R·

T))/Exp(−

Eb/(R·

T₀))

Rohm(T₀)=(Rohm(T)−

R1)×

Exp(−

Ec/(R·

T))/Exp(−

Ec/(R·

T₀))+R1

4. The method according to claim 1, wherein in the calculating, the reaction resistance component, the ohmic resistance component, and the diffusion resistance component are calculated by a regression calculation by using predetermined data indicating a relationship between the charged capacity and the diffusion resistance of each active material, predetermined data indicating a relationship between the charged capacity and the reaction resistance of each active material, and predetermined data indicating a relationship between the charged capacity and the ohmic resistance of each active material.

5. The method according to claim 1, wherein in the calculating, the reaction resistance component and the diffusion resistance component are calculated by using predetermined data indicating a relationship between the charged capacity and the reaction resistance of each active material, and predetermined data indicating a relationship between the charged capacity and the diffusion resistance of each active material, and a residual between the reaction resistance component and the diffusion resistance component is used as the ohmic resistance component.

6. The method according to claim 1, wherein in the calculating, the ohmic resistance component and the diffusion resistance component are held constant, and a residual between the reaction resistance component and the diffusion resistance component is used as the reaction resistance component.

7. The method according to claim 1, wherein in the calculating, the ohmic resistance component and the diffusion resistance component are estimated by a function of an accumulated time or an accumulated power amount, and a residual between the reaction resistance component and the diffusion resistance component is used as the reaction resistance component.

8. A cell performance estimation apparatus comprising:

a storage unit configured to store data obtained by measuring a cell temperature, an electric current, and a voltage while a secondary cell is charged or discharged;

an estimation unit configured to estimate an internal resistance value of the cell buy using the cell temperature data, the electric current data, and the voltage data, and predetermined data indicating a relationship between a charged capacity and open circuit voltages of a cathode active material and anode active material;

a calculation unit configured to calculate a reaction resistance component, an ohmic resistance component, and a diffusion resistance component from the estimated internal resistance value; and

a correction unit configured to correct the estimated internal resistance value based on a value obtained by correcting the reaction resistance comment, the ohmic resistance component, and the diffusion resistance component in accordance with a temperature, and adding up the corrected values.

9. The apparatus according to claim 8, wherein the estimation unit corrects the data indicating the relationship between the charged capacity and the open circuit voltages of the cathode active material and anode active material in accordance with a temperature based on data indicating a relationship between an entropy value of each active material and the charged capacity, with respect to a cell temperature at which the data indicating the relationship between the charged capacity and the open circuit voltages of the cathode active material and anode active material is measured.

10. The apparatus according to claim 8, wherein when using coefficients Ea, Eb, Ec, and R1 to be used in the temperature correction of the secondary cell and a cell temperature T, the correction unit performs temperature correction of a reaction resistance component Rct, a diffusion resistance component Rd, and an ohmic resistance component Rhom at a reference temperature T₀ as follows:

Rct(T₀)=Rct(T)×

Exp(−

Ea/(R·

T))/Exp(−

Ea/(R·

T₀))

Rd(T₀)=Rd(T)×

Exp(−

Eb/(R·

T))/Exp(−

Eb/(R·

T₀))

Rohm(T₀)=(Rohm(T)−

R1)×

Exp(−

Ec/(R·

T))/Exp(−

Ec/(R·

T₀))+R1

11. The apparatus according to claim 8, wherein the calculation unit calculates the reaction resistance component, the ohmic resistance component, and the diffusion resistance component by a regression calculation by using predetermined data indicating a relationship between the charged capacity and the diffusion resistance of each active material, predetermined data indicating a relationship between the charged capacity and the reaction resistance of each active material, and predetermined data indicating a relationship between the charged capacity and the ohmic resistance of each active material.

12. The apparatus according to claim 8, wherein the calculation unit calculates the reaction resistance component and the diffusion resistance component by using predetermined data indicating a relationship between the charged capacity and the reaction resistance of each active material, and predetermined data indicating a relationship between the charged capacity and the diffusion resistance of each active material, and uses a residual between the reaction resistance component and the diffusion resistance component as the ohmic resistance component.

13. The apparatus according to claim 8, wherein the calculation unit holds the ohmic resistance component and the diffusion resistance component constant, and uses a residual between the reaction resistance component and the diffusion resistance component as the reaction resistance component.

14. The apparatus according to claim 8, wherein the calculation unit estimates the ohmic resistance component and the diffusion resistance component by a function of an accumulated time or an accumulated power amount, and uses a residual between the reaction resistance component and the diffusion resistance component as the reaction resistance component.